Density texture in Voxel to mesh?
I've tried it this way:


Create bezier curves with bevel, convert to mesh, you have pipes.
Create a cube, Boolean it with the pipes.
Sculpt with Dyntopo to give it smoothness and bumps.
Decimate the mesh to reduce the amount of vertices. Give your object a Shading > Smooth.
Give it its surface bumps with a Noise Texture.